I saw my pdoc on match.com a few years ago. I never told him because like you I was worried about his privacy (even my social worker friend advised me not to say anything). Match is like okcupid in thy they can see who looked at their profile, so he knew I saw it, but because it is his job to protect my privacy as s client, he never said anything. It did eventually become a non issue for me and we seemed to come to an understanding where he's reference his knowledge of online dating indirectly. It may be too difficult for you to keep it in - and if it's bothering you you shouldn't. If it's not addressed it will become the elephant in the room and your therapy may be less and less helpful (especially if you have major transference).

It's a weird situation for a lot of Ts who are dating since they of course have the right to date like everyone else. My pdoc was the one who suggested I try online dating in the first place - and then went on himself a month later. He was much more savvy (and sensitive, I think) than your T in that he only posted a photo and info he was comfortable with clients seeing. It may have also been to avoid encouraging transference.

We were both off the site for a bit then both back on and I saw his profile again - this time with a much more personal write up and a shirtless photo! That is when I realized he was very purposeful in keeping the original profile kind of bland. He probably got fewer responses but it is the downside of being in the field. They always need to take clients into consideration when putting themselves out there on a public site.